Branched polyethyleneimine

The polymerization of A/-(2-tetrahydropyranyl)aziridine with subsequent hydrolysis of the resulting polymers has been described as an alternative route for the synthesis of linear polyethyleneimine (359). Linear polyethyleneimine, in contrast to branched polyethyleneimines, is only sparingly soluble in water at room temperature. 

The polymer was 10 times as effective as a small-molecule analog, dimethy-benzylamine 10 in the case of p-nitrophenyl caproate 6. The rate enhancement is larply attributed to favorable binding. No difference in catalytic activity was found between linear and branched polyethyleneimine derivatives. It is curious that desorption of the product is rate-limiting according to the kinetic analysis. 

In contrast to polysulfides, cationic polymerization is the only method to prepare high-molecular-weight polyamines. Polyethyleneimine is the only polymer commercialized among the group of cationically prepared polysulfides and polyamines. Branched polyethyleneimines, are used on the technical scale mostly as flocculants. 

For example, Dillon et al. [154] reported a covalent attachment of branched polyethyleneimine (PEI) to the sidewalls of SWNTs through the use of fluorinated single-wall CNTs as precursors. The structural integrity of the original purified SWNT is maintained upon covalent functionalization with PEI. Solid-state NMR shows the presence of carboxylate substituents due to carbamate formation as a consequence of the reversible CO2 absorption to the primary amine substituents of the PEI. Desorption of CO2 is accomplished by heating under argon at 75 °C, while the dependence of the quantity of CO2 absorbed on temperature and the molecular weight of the PEI is also observed. 

Ujiie S, Miyazaki W, limura K. Influence of spacer length on hquid crystal microstructures of branched polyethyleneimines with mesogenic pendent groups. Polym J 2012 44 561-6. 

Tan, S., Frol, M., Attygalle, A., Du. H. and Sukhishvfli, S. (2007) Synthesis of posihvely charged silver nanopartides via photoreduction of AgNOs in branched polyethyleneimine/HEPES soluhons. Langmuir, 23,9836-43. 

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